Ever consider they caved to being potentially sued for liable and the fact that the people sueing them had a pretty strong case?

But wait! What of freedom of speech?!?

I would say that, yes, the threat will be a suit of libel - but rather than the claimant (whomever it may be) having a strong case, it is more likely that the journal is attempting to limit any possibility of vicarious liability by publishing or endorsing it.

I can't really see how a person could sustain their cause here...and if it is utterly unfounded, I do not see why it cannot simply be rebutted with an article penned by an opposing scientist rather than resorting of legal action. If it is unfounded enough to warrant libel proceedings, it is unfounded enough for an educated scientist to rebut.